OLITS: An Ohm's Law-like traffic splitting model based on congestion prediction

Abstract

Through traffic splitting, multi-path routing in Network-on-Chip (NoC) outperforms single-path routing in terms of load balance and resource utilization. However, uncontrolled traffic splitting may aggravate network congestion and worsen the communication delay. We propose an Ohm's Law-like traffic splitting model aiming for application-specific NoC. We first characterize the flow congestion by redefining a contention matrix, which contains flow parameters such as average flow rate and burstiness. We then define flow resistance as the flow congestion factor extracted from the contention matrix, and use the parallel resistance theory to predicate the congestion state for every target sub-flow. Finally, the traffic splitting proportions of the parallel sub-flows are assigned according to the equivalent flow resistance. Experiments are taken both on 2D and 3D multi-path routing NoCs. The results show that the worst-case delay bound of target flow is significantly improved, and network congestion can be effectively balanced.